Advances in audio and video technology have led to the increasing popularity of portable digital audio and video players. iPod is a brand of portable digital audio and video player designed and marketed by Apple Computer and offers a simple user interface designed around a central scroll wheel. Most iPod models store media on a built-in hard drive, while the smaller iPod shuffle and iPod nano use flash memory. Like most digital audio players, an iPod can serve as an external data storage device when connected to a computer. Groups of audio and video coding standards employed in such devices include MP3 (MPEG-1 Audio Layer 3), AAC (Advanced audio coding), and Windows Media Audio (WMA).
No longer constrained to home computers, cassette tapes, CDs, and TVs, many people now store a large percentage of their music and video on portable digital audio players while away from home. Of course, much audio and video is still stored and played while at the home, and many people must choose between using a desktop computer while in the home and a portable digital audio and video player while away, or using a portable digital audio and video player exclusively, even while at home. Both options present disadvantages. Owning and operating a computer and a portable digital audio and video player involves additional expense, as two systems must be purchased and maintained. A high level of inconvenience is also introduced in that the two systems must be updated, that is, any music or video files added on one must be transferred to the other.